In general the inventive subject matter is directed to a multimode surgical instrument that provides for (1) multiple modes of electrosurgical operation, and/or (2) multiple modes of surgical treatment. In certain embodiments, the inventive subject matter is directed to a multimode electrosurgical system with a set of return electrodes that can be variably engaged into operation to control a temperature at select electrodes in the set or at a target area adjacent the electrodes. The inventive subject matter, while adaptable to many surgical and therapeutic applications, is particularly suited for use in a system for liposuction. Accordingly, hereafter, a liposuction application will generally be used to illustrate the principles of the inventive subject matter and various possible embodiments thereunder.
In general, a liposuction procedure involves the insertion of a cannula into an area of a patient's body where subcutaneous fat tissue 1 is present. The cannula includes a valve assembly that couples to a suction source. The operator applies suction to the cannula or other hollow shaft to remove fatty tissue that is disrupted by a disrupter associated with the cannula. The disrupter may be a mechanical element, such as blade, or an energy emitter for disruption by targeted energy. For example, the tip of a cannula can be configured to scrape fat tissue. In other known systems, the cannula supports a laser device or ultrasonic device for targeting disruptive energy into tissue to fragment, melt, or vaporize tissue. One disadvantage of typical laser-liposuction devices is that the laser fiber is in placed in the main channel or lumen of the cannula so there cannot be simultaneous melting of fat by the laser and suction of the disrupted fatty materials.
Liposuction procedures may be dry field, wet field, or semi-wet field procedures. In a dry field, the cannula is inserted into the target area without the introduction of any fluid. In a wet field, a fluid is introduced into the target area through a lumen in the instrument. The introduced fluid may serve various functions. For example, it can be an irrigant that facilitates the suctioning of disrupted tissue. A semi-dry field is one where the target area is lightly irrigated. Accordingly, in a liposuction procedure the suctioned material may be primarily fatty material or a mixture of fatty material and an introduced fluid.
A significant disadvantage of all liposuction procedures is that when subcutaneous fat is removed from below the dermis, skin tension is reduced causing unsightly wrinkling, sagging or other surface irregularities in the skin. The degree of such irregularities may necessitate a surgeon to excise skin tissue and suture the exposed edges to tighten the skin surface. This is highly undesirably on several fronts, including the creation of scars and additional surgical risk.
Accordingly, there is a need for improved surgical and therapeutic instruments that simultaneously address multiple surgical and therapeutic needs. In the case of liposuction, there is a need for systems and instruments that not only meet the requirements for disruption and removal of fatty tissue, but also mitigate the cosmetic impact of liposuction on the skin's appearance.